Ray Allen c. 2007, coming off ankle surgery, was an all star. He was a threat to turn the corner off of picks and go down the lane. Not any more. He has decent handles and passing for a wing/guard. That's about it. Currently, his only lethal threat is shooting and generally smart play.
Lee is a significant upgrade over 2012 Ray Allen.
I suspect Ray looked better than he was at the beginning of the year due to everyone else being out of shape, too.
At this point, Lee is better. He won't have a HOF career, but he's a legit starter that fits well, unlike Ray. He'll play end-to-end, not 3pt line-to-3pt line.
In short, we upgraded considerably.
Ray knows it, too. If he thought he could carry any part of the load, he wouldn't have to tag along with the stooges in Miami.